Currently solid-state devices are able to provide only about 10 milliwatts of output power in the 200 to 300 GHz band. Travelling wave tubes (“TWT”) still remain the preferred solution to generate high power over a wide spectrum in this frequency band.
Folded waveguides, staggered double grating waveguides and sine waveguides have all been demonstrated in terahertz TWTs, with cylindrical or sheet electron beams in the 100 to 850 GHz frequency range. Such waveguides have to be fabricated in two (or more) precision parts with the sealing edge critical to confinement of the propagating electromagnetic field. A very high precision assembly process is required (to eliminate misalignments that could perturb the wave propagation). New structures are desired with simpler assembly in order to lower the costs and improve repeatability and reliability.
Mineo & Paoloni (IEEE Transactions on electron devices, Vol. 57, no. 11, 3169, November 2010) propose a linear rectangular double-corrugated waveguide (“LDCW”) slow-wave structure for terahertz vacuum devices. That device comprises two linear rows of pillars.